Extraction of hydrocarbon oils



Patented May 23, 1933 UNITED STATES PAT ENTJ- OFFICE EDWIN R. IBIBKHIMER, OF PHILADELPHIA, PENNSYLVANIA, ASSIG-NOR TO THE ATLANTIC REFINING- COMPANY, OF PHILADELPHIA, PENNSYLVANIA, A. CORPORA- extremes.

TION OF PENNSYLVANIA EXTRAGTION OF HYDROCABBON OILS R0 Drawing.

The present invention relates to the art of mineral oil refining, and has particular reference to the separation of crude petroleum or petroleum products into fractions of different chemical compositions while of approximately the same distillation range.

In accordance with my invention, crude petroleum or petroleum products, particularly oils of substantial viscocity, are separated into various fractions by means of fractional extraction with an aliphatic aldehyde or mixture of aliphatic aldehydes, or mixture of solvents containing substantial quantities of aliphatic aldehydes.

It is recognized in the art that mineral oils, such as pertoleum, comprise essentially a mixture of hydrocarbons of various groups or homologous series of compounds, such for example, as parafins of the general formula C H olefines of the general formula C I-1 hydroaromatics and polymethylenes of the same empiricalformula, and various other series of compounds of chain and/or ring structures in which the hydrogen to carbon ratio is less than in the foregoing series. A large number of individual compounds of each series and of differing boiling points are present in petroleum.

The various types of crude petroleum, which are generally classified into three groups, namely, parafiinic base, naphthenic or asphaltic base, and mixed base, contain the various series of hydrocarbons mentioned heretofore in different proportions. For example, in the parafiin base crude oils, such as those obtained from the oil fields of Pennsylvania, there is a relatively'high proportion of hydrocarbons having a chain structure and a high hydrogen to carbon ratio, whereas in the naphthenic or asphaltic base crude oils, there is a relatively large proportion or hydrocarbons having ring structures and a low hydrogen to carbon ratio. Mixed base crude oils, such as are obtained from the Mid-Continent oil fields, contain hydrocarbons in proportions intermediate these two As the use of practically all of the petroleum oils is almost entirely physical, the above described chemical nature of those 1931. Serial No. 539,132.

oils is important in reflecting certain physical characteristics.

The variance in the proportion of he different series of hydrocarbons in pa aflinic, naphthenic, and mixed base oils is evidenced by the physical properties of the various oils and particularly by the relationship of the specific gravity to the viscosity of one oil as compared with another. For example, oils derived from a Pennsylvania crude and having a viscosity of 400 seconds Saybolt universal at 100 F., will show a specific gravity at 60 F. of about 0.878, whereas an oil of corresponding viscosity produced from a naphthenic crude, such as one from the Gulf coast area, will show a specific gravity of about 0.933 at 60 F. The relationship between the viscosity and gravity indicates the degree of the paralfinic or naphthenic character of the oil.

If a given crude petroleum be separated by distillation into successive fractions and the specific gravities and viscosities of the several fractions determined, it will be found tllglt they conform to the general relations p:

in which G is the specific gravity at 60 F., V is Saybolt universal viscosity at 100 F., and a is a constant known as the viscosity-gravity constant. Fractions from each of the different types of crude have different viscosity-gravity constants. Such constants are lower for fractions of the parafinic crudes than are the constants for fractions of the naphthenic crudes. An article entitled The viscosity-gravity constant of petroleum lubricating oils by J B. Hill and H. B. Coats, which will be found in volume 20, page 641 et seq., Industrial and Engineering Chemistry for June, 1928, explains the determinationof such constant for several typical 01 s.

The viscgsity-gravity constant is, therefore, an in ex of the paraflinicity or naphthenicity of an oil, sincewhen a given crude is distilled and fractions thereof are collected,

regardless of the fraction upon which the 'a partial separation of t drocarbons from the paraflinic, and to obtain specific gravity and the viscosity are taken, when such specific gravity and viscosity are substituted in the formula and the viscositygravity constant the fraction calculated, the constant will be substantially the same for each of the several fractions of the crude.

The viscosity-gravity constants of the viscous fractions for some of the typical crudes are as follows:

Milltown (Pennsylvania) 0.8067 Burbank (Mid-Continent); 0.8367 Guadalupe (Gulf Coast) 0. 8635 Mirando (Gulf Coast) 0.9025

These 'oils are increasingly paraflinic as the viscosity-gravity constants decrease.

My invention is based upon the discovery that oils containing both the parafiinic series of hydrocarbons and the-various naphthenic series may be fractionally extracted with an aliphatic aldehyde. Propionaldehyde is the selective solvent that I prefer to use, however, other aliphatic aldehydes, such as acetaldehyde may be employed, and are considered within the scope of my invention. The various series of hydrocarbons possess a differential solubility in such solvents; the naphthenic hydrocarbons are much more soluble therein than the paraflinic hydrocarbons. By means of extraction with an aliphatic aldehyde, and more particularly with propionaldehyde, it is, therefore possible to effect he naphthenic hyfrom an oil containing both classes of hydrocarbons, an oil which is much more paraflinic than the original oil and one which is much more naphthenic. By my invention, for example, it is possible to produce an oil. of the quality normally obtained from Appalachian crudes, from crudes of the mixed base type from the Mid-Continent area, and, conversely, to obtain oils from mixed base crudes such as are normally obtained from the naphthenic oils of the gulf coast area.

In practicing my invention, I prefer to mix the oil fraction to be treated with a suitable proportion of an aliphatic aldehyde or mixture of them, and more particularly with propionaldehyde at a temperature sufliciently high so that complete solution is effected and a homogeneous liquid obtained. I then cool the mixture to a temperature sufiiciently low to cause a separation of the liquid into a twolayer system the upper layer being a solution of a relatively small amount of the aliphatic aldehyde in the more paraffinic portion of the oil, and the lower layer comprising a solution of the more naphthenic portion of the oil in the aliphatic aldehyde. Instead of this heating and cooling to effect extraction, I may simply agitate the mixture of liquids at normal temperatures. Where substantial quantitles of solid hydrocarbons belonging to the true paraflin series (G H3 +2) are present, these solids or waxes remain in the upper layer and may cause it to be solid or semisolid. Separation of the two layers is then efiected, for example, by decantation, and the aliphatic aldehydes removed from each of the separated oil layers by vacuum distillation or other suitable procedure, thereby obtain .oils of progressively increasing parafiinicity as evidenced by a decreasing viscosity-gravity constant. In wax-bearing oils, the final undissolved product is a mixture of solid and liquidhydrocarbons. While the exact chemical compositions of these compounds are not known, it is probable that the liquid hydrocarbons are branched chain hydrocarbons of the paraffin series, whereas solid bodies are straight chain paraflin hydrocarbons. This product may be further separated into solid and liquid hydrocarbons by any of the well-known dewaxing processes, such as the cold settling process.

In many instances, it will be found of advantage to dewax the oil prior to the extraction process, as this expedites the manual operation of the latter.

My invention will be further understood from the following specific example:

100 parts of a previously untreated distillate obtained from a Gulf Coast crude oil and having a viscosity of 612 seconds Saybolt universal at 100 F., a specific gravity of 0.9303, and a consequent viscosity gravity constant of 0.87 4 was mixed with 100 parts of propionaldehyde and heated to slightly above the temperature of complete miscibility. The homogeneous liquid which resulted was cooled with agitation to 0 C., and allowed to settle whereupon a two layer system formed, which consisted of an upper undissolved oil layer comprising 122.4 parts of the mixture and a lower layer of oil dissolved in propionaldehyde comprising approximately 77.6 parts of the mixture. After separation, the layers were each freed from ropionaldehyde by vacuum distillation. he propionaldehyde dissolved fraction yielded 62.7 parts of propionaldehyde and 14.6 parts of oil having a viscosity of 1082 seconds Saybolt universal at 100 F., a s iecific gravity 1 an oil having a viscosity of 495 seconds Saybolt universal at 100'F., and a specific gravity gravity of 0.9218, and a viscosity gravity constant of 0.867. I

From the above example it will be seen that by a propionaldehyde extraction there may be obtained oil fractions which are respectively higher in paraflinicity and naphthenicity than the original oil. By repetition of the extraction process upon the propionaldehyde undissolved fraction, oils may be obtained which are increasingly parailinic, as evidenced by progressively decreasing viscosity-gravity constants.

It is evident that my process is practically independent of the particular nature or source of the crude oil, and that there may be produced thereby oils of desired characteristics from oils which heretoforehave not been used as a source of oils of such desired characteristics.

For example, my process may be employed to produce from petroleum of a mixed base type such as would, on normal batch distillation, give a residuum with a viscosity of 150 seconds Saybolt universal at-210 F. with a specific gravity of 0.928 or more, a lubricating stock with a viscosity at 210 F., of 150 seconds Saybolt universal, or more, and a specific gravity not higher than 0.910. This latter combination of properties is typical of cylinder stocks produced from Pennsylvania crudes.

In extracting oils containing appreciable amounts of wax, such oils may be dewaxed, for example, by cold settling or centrifuging prior to carrying out the extraction. My

1 procem is operable, however, in the absence of preliminary dewaxing. V

Hereinabove, mixtures of solvents have been referred to. It is to be understood that in such mixtures the constituent solvents will not react with one another, nor with the oil upon which they are to be used, and that such mixtures will contain substantial amounts 'ofan aliphatic aldehyde.

For brevity, in the appended claims, the

term aliphatic aldehyde is employed in ageneric senseto include one or a mixture of aliphatic aldehydes, or a mixture of solvents which contains substantialquantities of aliphatic aldehydes.

Also where herein and in the appended claims, an oil is specifically referred to as being viscous, it is to be understood that the oil is of substantial viscosity, i. e., of the order of 50 seconds Saybolt universal at 100 F., or more.

What I claim is: p

1. In the art of refining mineral oils,,the

process which comprises separating an oil containing paraflinic and naphthenic hydrocarbons into fractions respectively richer in paraflinic and naphthenic compounds by extracting said oil with an aliphatic aldehyde.

ture to such temperature as 2. In the art of refining mineral oils, the process which comprises fractionally extracting an oil containing paraflinic and naph thenic hydrocarbons with an aliphatic aldehyde to produce fractions of the oil respectively richer in paraifinic and napthenic compounds.

3. In the art of refining mineral oils, the process which comprises adding an aliphatic aldehyde to an oil containing paraflinic and naphthenic hydrocarbons, heating the mixto efi'ect solution, cooling the solution toform a two layer system, and separating the upper layer from the lower layer.

4. In the art of refining mineral oils, the process which'comprises adding an aliphatic aldehyde to an oil containing paraflinic and naphthenic hydrocarbons, heating the mixture to such temperature as to efl'ect solution, cooling the solution to form a two layer system, removing the lower layer, and similarly retreating. the upper layer with an aliphatic aldehyde.

5. In the art of refining mineral oils, thecarbons into fractions which comprises bringing the oil into contact with an aliphatic aldehyde, thereby to effect solution of a portion of the oil richer in naphthenic hydrocarbons in the aliphatic aldehyde, separating the solution so formed from the remainder of the oil, and distilling the aliphatic aldehyde from both of the portions ofthe oil, thereby to obtain fractions of the oil respectively richer in paraflinic and naphthenic hydrocarbons.

7. In'the art of refining mineral oils, the 5 process which comprises'bringing a mineral oil containing paraflinic and naphthenic hydrocarbons into contact with an aliphatic al-' dehyde, thereby to effect solution of a portion richer in naphthenic hydrocarbons in. n

the aliphatic aldehyde, separating the solution so formed from the remainder of the oil, and retreating the oil remaining with adv ditional amounts of an aliphatic aldehyde.

8. The method of producing paraflinic lubricating oil from mixed base crude which comprises distilling the crude and bringing a portion thereof into contact with propionaldehyde, thereby partially dissolving the oil, separating the propionalde'hyde solution of hyde from the treated oil.

9. The process'of producing a lubricating stock of specific gravity less than .910 and of Saybolt universal viscosity greater than 150 seconds at 210 F. from a' crude petroleum which on normal distillation yields a residuum of 150 seconds Saybolt universal viscosity at 210 F. and a specific gravity greater than .928, which comprises producing a residuum from the crude petroleum, and extracting said residuum from said crude petroleum with propionaldehyde.

10. In the art of refining mineral lubricating oil containing paraflinic and naphthenic hydrocarbons, the step of fractionallv extracting the oil with propionaldehyde, to effect separation of fractions respectively richer in paraflinic and naphthenic compounds.

'11. The process of producing a lubricating stock of specific gravity less than .910 and of Saybolt universal viscosity greater than- 150 seconds at 210 F. from a crude petroleum which on normal distillation yields a residuum of 150 seconds baybolt universal viscosity at 210 F. and a specific gravity greater than .928, which comprises separating a residuum from said crude petroleum and bringing such residuum into contact with propionaldehyde, to effect solution of a portion thereof with the propionaldehyde, separating the prooionaldehyde solution of oil from the portion which does not dissolve therein, and removing the propionaldehyde from the oil of said solution.

12. In a process for separating a viscous mineral oil containing parafiinic and naphj thenic hydrocarbons into fractions which are tracting the viscous respectively richer in naphthenic hydrocarhens and uarafiinic hydrocarbons other than wax, the step which comprises extracting the oil with propionaldehyde.

13. In a process for separating viscous mineral oil liquid at ordinary temperature containing parafiinic and naphthenic hydrov carbons into fractions respectively richer in paraflinic and naphthenic hydrocarbons, the

step which comprises extracting the oil with propionaldehyde.

14. In a process for separating a substanaldehyde, and separating the oil-so treated into portions respectively richer in paraflinic and naphthenic hydrocarbons.

16. The process of treating a viscous fraction of a mixed base crude oil to procure a fraction having the quality of a corresponding fraction of a paraifinic base crude, which comprises extracting the viscous fraction with propionaldehyde, and separating the oil so treated into portions respectively richer in parafiinic and naphthenic compounds.

17 In the art of refining mineral oils, the process which comprises adding propionaldehyde to a viscous oil liquid at ordinary temperatures containing paraflinic and naphthenic hydrocarbons, heating the mixture to a temperature suflicient to efiect solution, cooling the solution to a temperature sufficient to form two layers respectively richer in naphthenic hydrocarbons and paraflinic the upper layer richer in paraflinic hydrocarbons from the lower layer richer in naphthenic hydrocarbons.

18. In the art of refining mineral oils, the process which comprises adding propionaldehyde to a viscous oil liquid at ordinary temperatures containing paraflinic and naphthenic hydrocarbons, heating the mixture to a temperature sufficient to effect solution, cooling the solution to a temperature sufficient to form two layers, separating the propionaldehyde and paraflin wax from the from the upper layer, and separating the propionaldehyde from the lower layer to produce one fraction richer in parafiinic and a second fraction richer in naphthenic hydrocarbons than said viscous oil.

In testimony whereof I aflix my signature. EDWIN R. BIRKHIMER.

tially wax free viscous Imneral oil containing parafiinic and into fractions respectively richer in parafiinic and naphthenic hydrocarbons, the step which com rises extracting the oil. with propionalde yde.

, 15. The process of treating a viscous fraction of a crude oil of One t e containing paraflinic and naphthenic hy rocarbons to procure a fraction having the quality of a corresponding fraction of a crude oil of different type having a greater content of paraflinic hydrocarbons, which comprises exfraction with propionnaphthenic hydrocarbons 

